<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>5.字符串indexOf方法</title>
    </head>
    <body>
        <script type="text/javascript" >
            let str = 'abc'

            let x = str.indexOf('')
            console.log(x)
        </script>
    </body>
</html>